Home Cosmetic Science Talk Formulating How much ethanol to preserve formulas and solubilize SA without being drying?

  • How much ethanol to preserve formulas and solubilize SA without being drying?

    Posted by zink on March 5, 2020 at 1:48 pm

    Have a pH 3.8 formula with AHA and BHAs incl citric acid, need to preserve it and solubilize 2% SA better.

    Wondering how much ethanol is likely to do the trick, 5 - 10 or 15%? Less is better. The acids will also help with preservation. Will then do USP51 testing once the crystallization issue is solved.

    alchemist01 replied 3 years, 12 months ago 3 Members · 4 Replies
  • 4 Replies
  • alchemist01

    Member
    March 5, 2020 at 3:25 pm

    Not sure what you’re making, but I imagine for anything skincare-related ethanol would be not ideal. Propylene glycol is a good enough solvent for SA at low %s and works as a co-preservative.

  • zink

    Member
    March 5, 2020 at 8:35 pm

    Why not, 5 - 10% ethanol shouldn’t be drying? Propylene Glycol is a poor sollubilizer no, you’d need 15% or so?

  • EVchem

    Member
    March 6, 2020 at 11:49 am

    I got 2% SA into solution with 1.5% propanediol and 1% euxyl pe 9010 (which is the preservative I had to include anyway). I’m sure you could do it with just extra propanediol and avoid alcohol

  • alchemist01

    Member
    March 6, 2020 at 1:13 pm

    Zink said:

    Why not, 5 - 10% ethanol shouldn’t be drying? Propylene Glycol is a poor sollubilizer no, you’d need 15% or so?

    Sorry, I interpreted the question as looking for a preservative and solvent for SA in one. Ethanol as a preservative would have to be higher than I’d want it, not so much for drying but scent and viscosity effects.
    If you want to dissolve the SA in a smaller amount of ethanol and add it in it should be fine.

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